The invention relates to aluminum alloys which contain magnesium and silicon in the general range 0.3-1.0 wt.% magnesium and 0.3-1.2 wt.% silicon. Such heat-treatable alloys are utilized in most of the manufacturing processes used with aluminum alloys for example for manufacturing extruded, rolled and hot formed parts. Such products can be subjected to a heat treatment to achieve higher strength values. The silicon and magnesium contents are selected according to the strength desired likewise the concentrations of other alloying elements; for example up to 1.0% manganese, up to 1% copper or up to 0.35% chromium is added. It is also known to make vanadium additions in particular to reduce the quench sensitivity of extruded products. This makes it possible to dispense with water cooling after extrusion without having to accept a penalty in terms of strength.
All these measures employed to achieve a certain strength level are taken at the expense of one or more other desireable properties such as toughness, bendability, resistance to corrosion and, in particular in the case of extruded products, uniform surface, absence of die pick-up, good longitudinal weld seams, possibility to extrude complicated sections and implementation of economic extrusion rates.